Polysubstituted dihydropyrenes

ABSTRACT

Photochromic 1,3,6,8-tetra(lower)alkyl-15,16-dimethyl-15,16dihydropyrenes, 15,16-methylene-15,16-dihydropyrenes, 15,16methylene-15,16-dihydropyrenes, 15,16-methylene-15,16dihydropyrenes and 1,3,6,8-tetra(lower)alkyl-15,16-methylene15,16-dihydropyrenes substituted in one or both of the 2- and 7positions benzoyl, alkanoyl, alkanoyloxy, cyano, nitro, alkyl, Alpha -hydroxyalkyl, Alpha -acyloxyalkyl, Alpha isonitrosoalkyl, or acylamido groups are prepared via substitution of the parent hydrocarbon. A typical embodiment is 2-acetamido-7-nitro-1,3,6,8,15,16-hexamethyl-15,16dihydropyrene.

United States Patent [22] Filed:

Hall et al.

[541 POLYSUBSTITUTED DIHYDROPYRENES [72] inventors: Luther A. R.'l-iall,Woodcliff Lake,

N.J.; John A. Gurney, Tarrytown, N.Y.; Harris 8. Renfroe, Montvale, NJ.

[73] Assignee: Clba-Geigy Corporation, Ardsley,

Oct. 16, 1970 [211 App]. No.: 81,608

Related US. Application Data [60] Division of Ser. No. 635,287, April 7,1967,

Pat. No. 3,557,2l8, which is a continuation-inpart of Ser. No. 499,064,Oct. 20, 1965, abandoned.

[52] US. Cl ..260/6l8 F, 260/486 R, 260/599, 260/606.5 F, 260/619 F,260/668 F [5i] Int. Cl. ..C07c 35/22, G03f 5/00, F2lv 9/00 Profit et aL,Chem. Abstracts Vol. 60, (1964), p. l669,QD1A5l.

Boekelheide et al., J. Am. Chem. Soc.," Vol. 85, (1963) Pp- 1545,1546,QD1A5.

Boekelheide et aL, J. Am. Chem. Soc., Vol. 89, (1967) pp. 1695 to 1704,QDlAS.

Primary ExaminerLeon Zitver Assistant ExamincrJoseph E. EvansAttorneyl(arl F. Jorda et a1.

[57] ABSTRACT Photochromic l ,3,6,8-tetra(lower)alkyll 5 l 6-dimethyl-15,16-dihydropyrenes, 15,16-methylenel 5,16-dihydropyrenes, l5, l 6 methylenel 5, l 6- dihydropyrenes, 15,16-methylene-l5, l6-dihydropyrenes and 1,3,6,8-tetra(lower)alkyl-15,16methylene-l5,l6dihydropyrenes substituted in one or both of the 2- and7-positions benzoyl, alkanoyl, alkanoyloxy, cyano nitro, alkyl,a-hydroxyalkyl, a acyloxyalkyl, a-isonitrosoalkyl, or acylamido groupsare prepared via substitution of the parent hydrocarbon. A typicalembodiment is 2-acetamido-7-nitro- 1 3,6,8, 1 5 l 6-hexamethyll5,16-dihydropyrene.

1 Claim, No Drawings POLYSUBSTITUTED DIHYDROPYRENES CROSS REFERENCE Thisis a division of copending application Ser. No. 635,287 filed Apr. 7,1967 and now US. Pat. No. 3,557,218, which in turn is acontinuation-in-part of application Ser. No. 499,064 filed Oct. 20, I965and now abandoned.

DETAILED DESCRIPTION This invention relates to organic compoundsreversiblyconvertible from colored to colorless isomeric forms.

More particularly, this invention pertains to l5,l6- dihydropyrenes,which are photochromic. Thus these compounds when exposed to lightbecome colored or colorless depending on their structure, and, whenwithdrawn from light revert to their original state. These compoundsaccordinglyfind application as selfattenuating light valves in articlessuch as tinted safety glass and headlights for automobiles; infraredscreens,

solarium windows, display windows, and automatic curtains; ininformation retrieval apparatus such as computer memory core devices,toys, photocopying devices, light meters, and the like.

The fundamental pyrene nucleus of the compounds of the present inventionis numbered as follows:

. 4 The compounds of the present invention are represented by thefollowing formulas:

wherein R is hydrogen or (lower)alkyl;

Q is benzoyl, (lower)alkanoyl, (lower)alkanoyloxy, cyano, nitro,aisonitroso(lower)alkyl, a-hydroxy(lower)-alkyl,a-(lower)alkanoyloxy(lower)alkyl, alower )alkenoyloxy-( lower)alkyl, or(lower )alkanoylamido, and 7 Q is hydrogen, benzoyl, (lower)alkanoyl,(lower)- alkanoyloxy, cyano, nitro, a-isonitroso(lower)alkyl, a-

corresponding alkanoyl hydroxy-(lower)alkyl,a-(lower)alkanoyloxy(lower)alkyl, a-(lower)-alkenoyloxy(lower)alkyl, or(lower)al- I kanoylamido.

By the term alkyl," and derivations thereof employing the root alk," ismeant a branched or straight chained saturated hydrocarbon chain of upto about 30 carbon atoms, or a group containing such a chain.Representative of such alkyl groups are thus methyl,

ethyl, propyl, isopropyl, butyl, s-butyl, t-butyl, pentyl,

hexyl, octyl, decyl, dodecyl, tetradecyl, hexadecyl, octadecyl, eicosyl,docosyl, tetracosyl, hexacosyl, octacosyl, triacontyl and the like. Itis to be understood that when required by the nature of certainfunctional groups, as for example, unsaturation in alkenyl, such groupswill contain at least two carbon atoms. When the term alkyl is qualifiedby the designation "lower," there is included branched or straight chainhydrocarbon groups of from one to about six carbon atoms.

The compounds of the present invention are prepared via mono ordisubstitution in one or more steps as hereafter described of atrans-l5,l 6-dimethyll ,3,6,8-tetra(lower)alkyl-l 5, l -dihydropyrene ora cisl 5, l 6-tnethylene-1 5 l 6-dihydropyrene, the latter nucleus beingoptionally tetrasubstituted by (lower)alkyl groups in the l, 3, 6 and8-positions. introduction of one or more acyl groups such as benzoyl,acetyl, propionoyl, butanoyl and the like is effected through treatmentwith the corresponding acid chloride or acid anhydride in the presenceof stannic chloride, optionally in an inert, non-aqueous solvent such asmethylene chloride, chloroform or the like. Thus for example the benzoylgroup is introduced through treatment with benzoyl chloride and stannicchloride while the acetyl, or other alkanoyl, group is introducedthrough treatment with acetic anhydride, or other alkanoic acidanhydrides, and stannic chloride. In the case of the formyl, there ispreferably employed butyl dichloromethyl ether, and stannic chloride.The butyl dichloromethyl ether may be obtained for example from n-butylformate and phosphorus pentachloride.

Compounds wherein one or both of Q and Q are aisonitrosoalkyl areobtained through the reaction of the compounds and hydroxylamine.Treatment of the oxime obtained from the formyl starting material withacetic anhydride yields the corresponding cyano compound.

The compounds of the present invention bearing a nitro group in the 2 or7-position are obtained through nitration, utilizing cupric nitrate andacetic anhydride. Reduction of the resulting nitro compound with zincdust and acetic acid/acetic anhydride yields the co rrespondingacetamido derivative (or with zinc and other alkanoic acid anhydrides toyield the corresponding alkanoylamido derivatives).

Reduction of the various alkanoyl derivatives of the present inventionas with lithium aluminum hydride and aluminum chloride yields thecorresponding alkyl 7 Pat. No. 3,390,192. Briefly in the case of the15,16- dimethyl-l ,3,6,8-tetra(lower)alkyl-15,16- dihydropyrene, thisinvolves initial preparation of a2,6-di(lower)alkyl-3,5-bis-(chloromethyl)-4- methylanisole, such as forexample 4,6-bis- (chloromethyl)-2-methoxymesitylene, alternatively namedas 2,4,6-trimethyl-3,5-bis- (chloromethyl)anisole. This generallycomprises treating a readily available or easily prepared 2,6-di(lower)alkyl-4-methyl-phenol with a 'methylating agent, such asdimethyl sulfate, followed by introduction of chloromethyl groups intothe two remaining unsubstituted positions. Replacement of the chlorineatoms by iodine atoms as through the action of sodium iodide then yieldsthe corresponding2,6-di(lower)alkyl-3,S-bis-(iodomethyl)-4-methylanisole, two molarequivalent amounts of which are coupled as through the action of sodiumand tetraphenylethylene to yield a 8,16-dimethyl-[2.2]metacyclophane ofthe formula:

OCH;

(lower)alky1 (lower)alkyl I OH;

(lower)alkyl (lower)alkyl it has now been further discovered thatelimination of several manipulative steps advantageously is possibleOCH:

HCHO/HCl ZnCh/LiCl in the foregoing conversion. Thus treatment of the 7OCH: 0 CH:

R R R R CICH - [2.21metacyclophane.

Thus prepared according to the foregoing procedures is the[2.2]metacyclophane of the structure:

O OH:

I) raga 0H,

Oxidation of the [2.21metacylophane of FORMULA ii A or II B with ferricchloride or with chromium trioxide and sulfuric acid then yields atetracyclic bis dienone which is oxidatively dehydrogenated with oxygenin the presence of base. Removal of the dione structure with lithiumaluminum hydride and aluminum chloride followed by dehydrogenation withpalladium then yields the desired l5,l6-dimethyl-l,3,6,8-tetra(lower)alkyll 5, l 6-dihydrop'yrene starting material.

The following preparations and examples are given solely for the purposeof illustration and are not to be construed as limitations of thisinvention, many variations of which are possible without departing fromthe spirit or scope thereof.

PREPARATIONI 1 ,3,6,9, 1 5,1 -liexamethyll 5 l 6-dihydropyrene (a)Methoxymesitylene 2,4,6-Trimethylphenol, 29.5 g, 0.217 mol, prepared bythe procedure of Hart and Beuhler, J. Org. Chem, 29, 2397 (i964), sodiumhydroxide, l2.6 g, 0.316 mol. dissolved in 126 ml of water, and 19.7 mlof dimethyl sulfate, 0.217 mol, are mixed in a vessel cooled in an icebath. The temperature is raised and maintained at 501:1" C for 1 hour,then 7.50 g of sodium hydroxide in an equal weight of water and ml (0.110 mol) of dimethyl sulfate are added at 3 hour intervals during hours.The product is isolated by extraction of the aqueous reaction mixturewith seven 75-ml portions of ether. After washing the ether layer with25 percent sodium hydroxide and evaporating the ether, the residue isfractionally distilled and 26.9 g of methoxymesitylene, b.p. 29 C/0.40.45 mm, 83 percent yield, is obtained.

(b) Bis(chloromethyl)methoxymesitylene A mixture of methoxymesitylene,7.4 g, 0.049 mol, paraformaldehyde, 7.82 g, 0.197 mol, lithium chloride,9.82 g, 0.245 mol, and zinc chloride, 4.80 g, 0.049 mol, is heated to 80C and anhydrous hydrogen chloride is passed in. Addition of gas iscontinued for 5-% hours at 72t2 C during which time monochloromethylatedproduct, which appears first, is converted to the desired bischloromethylated product. The reaction misture then is poured into 100ml of ice, and the solid material is collected on a filter and washedwith water. There is obtained 1 1.5 g ofbis(chloromethyl)methoxymesitylen e, 94 percent of theory.Recrystallization from ethyl acetate yields 9.05 g of product, m.p.135-l 36 C.

Alternatively this product is obtained via the following procedure: To198 g (1.32 mole) of 2-methoxymesitylene are added with stirring 1,400ml of concentrated hydrochloric acid and 78.4 g (0.87 mole) of strioxane(three mole equivalents formaldehyde); the resulting suspension isstirred at room temperature for 0.5 hours and a slow stream of hydrogenchloride is then passed through the stirred suspension which isbis(iodomethyl)methoxymesitylene, alternatively named as2,4,6-trimethyl-3,5-bis(chloromethyl)- anisole, m.p. l34-l 38 C, 69percent yield.

(d) 4,6,8,12,14,l6-l-lexamethyl-7,l 3-dimethoxy-[ 2.2]metacyclophaneBis(iodmethyl)methoxymesit ylene, 15g in 500 ml of dry tetrahydrofuran(Tl-1F) is added at 1 drop per second to sodium sand, g, 0.87 mol,suspended in 1 liter of refluxing THF and 2 g of tetraphenylethylene.The system is stirred under nitrogen with a Vibromixer stirrer.Unreacted sodium is filtered off and the THF is removed by distillationin such a way that the pot temperature remains at or below C. Theresidual solid is dissolved in 250 ml of methylene chloride. Thesolution is percolated through 15 g of Florisil, then the methylenechloride is evaporated off leaving a residue, which is dissolved inwarmed on a steambath for 12 to 15 hours. The reaction slurry is thencooled and stirred in an ice bath, the crude product being collected byfiltration. The collected solid is broken up and washed several timeswith water to remove hydrochloric acid, dissolved in methylene chlorideand this solution is washed several times with a saturated sodiumbicarbonate solution, followed by several washings with brine, dried,clarified with charcoal, and concentrated. The resulting solid isslurried with heptane and collected by filtration. A second washing withheptane yields the product as white needles, 234.2 g (72 percent), m.p.l38l39. The analytical sample may be prepared by recrystallization fromheptane.

Anal. Calcd for C I- 0C1 2 C, 58.31; H, 6.53

Found: C, 58.33; H, 6.39

(c) Bis(iodomethyl)methoxymesitylene Bis(chloromethyl)methoxymesitylene,8.0 g, 0.0324 mol, sodium iodide, 40 g, 0.26 mol, and 400 ml oftetrahydrofuran are refluxed for 6 hours. The reaction solvent isremoved by distillation at 15 mm pressure. Methylene chloride, 100 ml,and 300 ml of ice water are added. The aqueous phase, after separationof methylene chloride, is extracted 4 times with 200 ml of methylenechloride. The combined organic layers are percolated through 200 ml ofcrushed calcium sulfate then treated with decolorizing charcoal. Themethylene chloride filtrate is concentrated in a vacuum to 30 ml volumeand 55 m1 of methanol is added. The precipitate is collected andrecrystallized first from toluene, and then from ethyl acetate to yield9.62 g of 30 ml of hot carbon tetrachloride. The solid whichprecipitates on cooling is collected and treated with 30 ml of hotcyclohexane. The cyclohexane solution is cooled and the desired productprecipitates. There is obtained 1 1.7 g of crude material, which ischromatographed on alkaline alumina. After rechromatographing, there isobtained 0.73 g of material, m.p. 22023lC.

Alternatively the [2.2]metacylophane is prepared as follows: A 3 literthree-neck flask equipped with a Vibromixer and condenser is flame-driedwhile the system is purged with a stream of prepurified nitrogen andallowed to cool under a positive pressure of nitrogen. To the flask areadded 200 ml of dry toluene, 20 g freshly cut sodium pieces and about 10drops of oleic acid. The oil bath temperatures is raised to l30l40; and,when all sodium has melted, agitation provided by the Vibromixer iscarried out for 15 minutes. At the end of this time agitation isstopped,

and the sodium sand allowed to cool without stirring. To this mixture isadded a solution of 750 mg of tetraphenylethylene in 300 mltetrahydrofuran (distilled from lithium aluminum hydride and stored oversodium), a deep red color forming immediately.

A 1 liter Hershberg dropping funnel is attached to the reaction vesselunder the same nitrogen pressure and a solution of 30 g of 4,6-bis(chloromethyl)methoxymesitylene in 700 ml of tetrahydrofuran is addedthrough the funnel at a rate of 20-25 drops/minute. Throughout theaddition, a slow agitation is provided by the Vibromixer. Addition of'the first charge is complete in 15 hours and a second charge of 30 g ofthe bis(chloromethyl) compound in 700 ml of tetrahydrofuran is thenadded over 15 hours. A few drops of ethanolare next added to destroy thered color and, after standing for several minutes to allow the unreactedsodium to settle, the milky-gray suspension is carefully'decanted frommost of the unreacted sodium into a large sintered-glass funnel preparedwith a tight Superce1 pad. The reaction flask and pad are washed withadditional tetrahydrofuran and the clear, colorless filtrate wasconcentrated, yielding a crystalline residue. This residue is dissolvedin 300 ml of methylene chloride and this solution is filtered, dilutedwith 300 ml ether, washed with 300 ml of 6N hydrochloric acid, dried,concentrated to a volume of 300 ml and applied to a 1.5 inch X 24 inchcolumn of dry-packed Florisil absorbent (60- 200 mesh). Of six 300 ml.fractions collected, fractions 2,3, and 4 are combined andrecrystallized twice from ethanol/heptane to yield the product as clear,colorless prisms, m.p. 234235.

Anal. Calcd for C l-1 C, 81.77; H, 9.15

Found: C, 81.71; H, 8.89

(e) Bis dienone The product of Step (d) is treated with ferric chloride.A solution of 1.00 g of the metacyclophane in 100 ml of dry chloroformis stirred at room temperature for 3 hours with 3.5 g ferric chloride. Aprecipitate of a reddish-brown inorganic complex of the bisdienone isformed and this is collected by filtration. This solid is immediatelysuspended in 100 ml chloroform and 20 ml 3 N hydrochloric acid. Thissuspension is shaken until solution occurs; the chloroform layer isseparated, washed with water and concentrated. The reddish brown solid,about 1.2 g, is treated with charcoal in boiling ethanol, filtered, andthe ethanolic solution is concentrated to about 20 ml. From the coldsolution separates 0.9-1.0 g of a yellow solid.

Alternatively this product is prepared as follows: A chromic acidsolution is prepared by treating 8.0 g of chromium trioxide with 3 to 4ml of water followed by 6.4 ml of sulfuric acid, and dilution with waterto a total volume of 30 ml. 15 milliliters of this chromic acid solutionare added dropwise to a stirred suspension of 6.7 g, (0.019 mole) of4,6,8,l2,l4,16-hexamethyl- 5,13-dimethoxy-[2.2]metacyclophane in 500 mlof acetone over 15 to 20 minutes. Near completion of the addition, agreen pasty precipitate forms which adheres to the side of the flask andstirrer blade. This suspension is stirred for 1.5 hours, during whichtime the precipitate becomes more solid and begins to break up. Thismixture is poured into 1 liter of water and stirred with 500 ml ofmethylene chloride; the light yellow organic layer is separated from thegreen aqueous layer, which is extracted with an additional 150 mlmethylene chloride. The combined extracts yields a crystalline lightyellow residue which is washed with acetone and collected by filtrationto yield the product, m.p. 34l-343. Recrystallization from chloroformraises the melting point to 345347.

Anal. Calc'd for C H O C, 81.95; H, 8.13

Found: C, 81.71; H, 8.07

(f) Quinone The product of Step (e) is treated with oxygen in thepresence of sodium hydroxide. A suspension of the bisdienone (190 mg) ina solution of methanol ml), water (15 ml), and sodium hydroxide (2.5) isstirred for 12 hours at room temperature. The resulting solution isconcentrated under reduced pressure, diluted with water (50 ml), andextracted with 20 ml methylene chloride. The blue aqueous layer isextracted again with solvent, and the combined organic extracts aredried and concentrated. The residue is sublimed at l80-200 (0.1 mm). Theorange sublimate is dissolved in chloroform, diluted with petroleumether, and after standing overnight at -l0 the resulting crystallineproduct (175 mg, 90) is collected.

(g) Hexaene The product of Step (f) is treated with lithium aluminumhydride and aluminum chloride. To a solution of 7 g of aluminum chloridein 120 ml of ether, 2 g of powdered lithium hydride is added withstirring and the suspension is boiled under reflux for 2 hours. Aftercooling, a 90 ml portion of the clear supernatant is withdrawn,transferred to a reaction flask and cooled to -80.

The quinone of step (f) (300 mg) in 10 ml benzene is added to 200 ml ofether and the suspension added drop-wise with stirring to the mixedreducing agent at 80 C over a 2 hour period. The suspension is slowlywarmed to room temperature and boiled for 0.5 hour. After destroying theexcess reagent with ethyl acetate followed by water, and separation ofthe ether layer, evaporation .under reduced pressure yields a greenresidue which is unstable to light and air.

(h) Dihydropyrene The product of Step (g) is treated with palladium anddehydrogenated. A suspension of mg of 5 percent palladium-charcoal in 25ml of benzene containing 1 ml of acetone is refluxed for 15 minutes. Tothis mixture is added 50 mg of the above green solid and heating iscontinued for 6 hours. The suspension is cooled, filtered, and theresidue remaining after removal of solvent is sublimed at l00/0.l mm,m.p. l84-l86 C, color change at about 240 C. The product may also bepurified through slurrying in methanol and recrystallizing from hexane.

PREPARATION ll 15,16-Methylene-l,3,6,8-tetramethyl-l5 ,16- dihydropyrenethe product, m.p. l72.5177 C which is further purified throughrecrystallization to 3:7 ethyl acetatezheptane, m.p. 175-178 C.

(b) 4,4'-Methylene bis-(2,6-dimethylanisole). Dimethyl sulfate (89 g) isadded dropwise over 1 hour to 90 g of 4,4'-methylene bis-(2,6-xylenol)and 42.4 g of sodium hydroxide in 425 ml water. Thereafter, 21.2 g ofsodium hydroxide and 46 g of dimethyl sulfate are I added to the mixture(5015 C) at hourly intervals, for

7 hours, after which 21.2 g of sodium hydroxide are added. A finalcharge of 89 g of dimethyl sulfate is added slowly and the mixture thenrefluxed for 1.5 hours. After cooling to room temperature, the solid iscollected and dissolved in a 400 ml of water, The other extract iswashed with 25 percent sodium hydroxide (2 X 25 ml) and with saturatedsodium chloride (2 X 25 ml), then dried overnight. Removal of solventand distillation from sodium affords the product in percent yield, b.p.l36l45/0.10 mm, m.p. 78-82 (c) 4,4-Methylene bis(3-chloromethyl-2,6-dimethylanisole) Hydrogen chloride is bubbled into a stirred mixture of16.9 g of trioxane, 19.2 g of lithium chloride in ml. of glacial aceticacid. After 10 minutes (exothermic from 25 to 38 C) the reaction mixturebecomes clear and homogenous. 10 grams of 4,4-methylenebis(2,6-dimethylanisole) are then added in one portion. The mixture isheated for 9% hour on a steam bath. The reaction slurry is mixed withice (200 ml) and filtered. The solid is dissolved in chloroform, washedwith 10 percent sodium bicarbonate solution to neutrality andevaporated. Recrystallization of the solid from ethyl acetate affordsthe product, 73 percent yield, m.p. -137 C.

(d) 4,4'-Methylene-3,3 l ,2-ethylene)-bis( 2,6- dimethylanisole Thecompound of step (c) (19.0 g, 0.105 eq. in absolute ether) is condensedupon addition to methyl magnesium iodide (methyl iodide 14.9 g,

liters of anhydrous toluene is added over a 68 hour period to asuspension of 60 g of molten sodium and l g of tetraphenylethylene in100 ml of tetrahydrofuran. The sodium is removed by filtration and thefiltrate is concentrated to yield the product which is recrystallizedfrom 20 percent chloroform in isopropanol, m.p. l40-l4l.5 C.

(e) 4,4'-Methylene-3,3'-( 1 ,2-ethylene)-bis[5,5'-bis(chloromethyl)-2,6-dimethylanisole] Anhydrous hydrogen chloride isbubbled into a mixture of trioxane (2.4 g) zinc chloride (2.7 g),lithium chloride (1.7 g) and glacial acetic acid (10 ml) to give ahomogeneous solution of his chloromethyl ether. 4,4'-Methylene-3,3 l,2-ethylene)-bis(2,6-dimethylanisole), alternatively named as l ,3 ,7,9tetramethyl-2,6-dimethoxy-5 H- dibenzo[a,d]cycloheptene, is added inone portion (3.1 g) and the temperature kept at 50il C for 8 hours. Theproduct is isolated by pouring the reaction mixture into ice (20 ml) andextracting with methylene chloride. The extracts are washed twice with10 ml portions of 10 percent sodium bicarbonate and twice with 5 mlportions of saturated sodium chloride solution, dried overnight andevaporated. The residue is chromatographed on alumina eluting with ethylether/hexane to yield the desired product and l,3,7,9-tetramethyl2,8dimethoxy-4-chloromethyl-5H- dibenzo[a,d]cycloheptene.

f) 4,6,12,l4-Tetramethyl-5,l3-dimethoxy-8,l6-methylene-[2.2l-metacyclophane. 1 gram of 4,4- methylene-3,3-(l,2-ethylene)-bis-[5,5'- bls(chloromethyl)-2,6-dimethylanisole] isallowed to react with zinc dust (0.l77 g), sodium carbonate (0.260 g)and a catalytic amount of sodium iodide to yield the 4,12-methylenemetacyclophane. The hot reaction mixture is poured into ice (100 g) andis extracted with methylene chloride. The extract is washed with water.After the solvent is stripped off, steam distillation provides about an80 percent yield of white needles.

Alternatively 5 ml of butyl dichloromethyl ether and 3 ml of stannicchloride are added to 7.1 g of l,3,7,9-tetramethyl-2,8dimethoxy-4-chloromethyl-5H- dibenzo[a,d]cycloheptene in300 ml of dry methylene chloride. After stirring for 24 hours themixture is poured into 500 ml of water, stirred for 30 minutes andextracted with 500 ml of ether. These extracts are washed with brine,dried 'over magnesium sulfate and concentrated. The residue is dissolvedin 200 ml of heptane, reconcentrated and recrystallized from methylenechloride/heptane to yield l,3,7,9-tetramethyl-2,8dimethoxy-4-chloromethyl-SH-dibenzo[a,d]cycloheptene-6-aldehyde, m.p. 205-206 C. This material (5.83g) and 3.95 g of triphenylphosphine are added to l75 ml of toluene andheated at reflux for 24 hours. The cooled slurry is filtered and driedto yield l,3,7,9-tetramethyl-2,8-methoxy-4- triphenylphosphoniummethyl-5l-I-dibenzo[ a,d]

cycloheptenealdehyde chloride, m.p. 222-224 C.

i To 9.29 g of this material in 300 ml of absolute ethanol is added in adropwise fashion under nitrogen and with stirring, 30 ml of a solutionprepared by dissolving 1.13 g of sodium in ml of ethanol. The sodiumethoxide is added over a 15 minute period and the mixture is thenrefluxed for 4 hours. The cooled mixture is filtered and the filtrate iscooled to 20 C and held there for 15 hours. The solid which forms iscollected by filtration and dried to yieldl,3,6,8-tetramethyl-5,l3-dimethoxy- 8, l 6-methylene-[2.21metacycloph-l2)ene, m .p. l84.5l 86 C. A solution of 635 mg of this material in ml ofethanol is hydrogenated in the presence of 250 mg of -5 percentpalladium-on-charcoal until the theoretical amount of hydrogen isabsorbed (about 90 minutes). The mixture is then filtered andconcentrated and the residue recrystallized from methanol to yieldl,3,6,8-tetramethyl-5, l 3-dimethoxy-8 ,1 6-methylene-[2.21metacyclophane, m.p. l53-155 C.

(g) Bis dienone The metacyclophane of step (f) (0.66 g) and anhydrousferric chloride (2.0 g, 1.2 mol) dissolved in anhydrous chloroform (80ml) are stirred at room temperature for 6 hours to give an insolublereddish brown complex. The complex is collected by filtration and isdecomposed by vigorously shaking with a mixture of chloroform (70 ml)dilute hydrochloride acid (3 N, 15 ml) until solution was complete. Theseparate chloroform layer is concentrated and the redbrown solid isdissolved in 70 ml of hot ethanol. The hot solution is treated withcharcoal and is concentrated to 15 ml. On cooling yellow needles aredeposited in about 90 percent yield.

(h) Quinone A suspension of the compound of step (g) (0.50 g, 1.63 mol)a water-methanol (70 ml, 150 ml) solution of sodium hydroxide (10 g,0.25 mol) is stirred for 18 hours at room temperature. The resultingsolution is concentrated under a water pump, diluted with water (200 ml)and extracted with methylene chloride (90 ml). The aqueous layer isextracted further (2 X 25 ml) and all extracts were combined, washedwith water, evaporated under a water pump and sublimed (l00 C/0.0l mm)to give a violet solid. Recrystallization from chloroform-cyclohexaneaffords orange needles in about 90 percent yield.

(i) l5,l fi-Methylene-l ,3,6,8-tetramethyl-l 5, l 6- dihydropyrene Areducing solution is prepared by adding lithium aluminum hydride (2.0 g)to an ether ml solution of aluminum chloride (7.0 g) stirring, refluxingthe mixture for 2 hours and then transferring 80 ml of cooledsupernatant liquid to a preassembled and dried reaction set-up. Dropwiseaddition of quinone of step (h) (0.340 g dissolved in 10 ml benzene anddiluted to 200 ml with dry ether) to the reducing solution mentionedabove at 80 C over 2 hours time yields a mixture of the desired productand a dihydro product. The suspension is warmed to room temperature (1hour) and then refluxed for A hour. The excess reducing agent isdecomposed with ethyl acetate and enough water (25 ml) is added to givetwo phases. The separated ether phase is dried under vacuum. Theresulting blue solid is then refluxed in cyclohexane (200 ml) with 30percent palladium-on-charcoal (0.300 g) for 18 hours to completedehydrogenation of the dihydro product. After filtration and removal ofthe reaction solvent the blue solid is sublimed (140l0.02 mm) to yieldthe product in about 60 percent yield.

EXAMPLEI 2-Nltl0-l ,3,6,8, l 5, l fi-hexamethyll 5, l 6- A dihydropyreneTo a stirred solution of 1.0 g of the dihydropyrene of Preparation in250 ml of acetic anhydride at 1.0 g

of powdered anhydrous cupric nitrate is added. The color changes overone-half hour from green to purple.

. After stirring 2 hours the product is isolated by dilution with 50 gof ice and extracted with 100 ml of ether. Evaporation of the solventleaves a residue which, after solution in hot methanol and dilution withhot water,

deposits the product as dark purple needles. The yield is about 85percent.

Further purification can be effected through chromatography on silicagel. Initial elution with 5 percent I methylene chloride/heptane yieldsthe starting material while further elution with 20 percent methylenechloride heptane yields the desired product, m.p. 224-226 C.

EXAMPLE I! 2-Acetylamino-1,3,6,8,l5 l 6-hexamethyl-1 5,16-

dihydropyrene To a stirred solution of the 2-nitro-compound of Example l(50 mg) and-0.2 g of sodium acetate in 5 ml of acetic anhydride is'added 0.5 g of zinc dust over a period of 5 minutes. The mixture isstirred for 1 hour, and water is then added and the mixture is extractedwith two 30 ml portions of methylene chloride. The combined extracts arewashed with dilute ammonium hydroxide, water, and after drying, thesolvent is removed. The residue is chromatographed on an alumina columnand the product is eluted with petroleum ether-methylene chloride. Theyield is about 90 percent.

Alternatively the crude residue may be purified by extraction withmethylene chloride/ether, evaporation and recrystallization frommethylene chloride/heptane.

EXAMPLE Ill methanol and is precipitated with hot water. The yield isabout 80 percent.

EXAMPLE 1v 2,7-Dinitro-l,3,6,8,l5,16-hexamethyl-l5,16- dihydropyreneZ-Amino-7-nitrohexamethy1dihydropyrene (prepared from the Z-acetylaminocompound of Example 111 by acid hydrolysis, 0.025 mole) is dissolved inl0-20 m1 of fluoboric acid in a 50 ml beaker, and the solution is cooledand stirred in an ice bath. A cold solution is 1.7 g (0.025 mole) sodiumnitrite in 4 ml water is added dropwise. After addition the mixture isstirred for 10 minutes and filtered by suction. The solid diazoniumfluoborate is washed with 30 ml cold fluoboric acid, then with 95percent ethanol and, finally, several times with ether. The product isobtained in about 95 percent yield.

20 grams of sodium nitrate is dissolved in 40 ml of EXAMPLE V2,7-Diacetylamino-l ,2,6,8, 1 5 ,1 6-hexamethyl-l 5,1 6- dihydropyreneTo a stirred solution of the 2-acetylamino-7-nitro compound of Example111 (500 mg) and 2 g of sodium acetate in 50 ml of acetic anhydride isadded 5 g of zinc dust overa 10 minute period. The mixture is stirredfor 1 hour, water is added, and the mixture is extracted with two 30 mlportions of methylene chloride. The combined extracts are washed withdilute ammonium hydroxide, water, and after drying of solvent overmagnesium sulfate, the methylene chloride is removed. The residue ischromatographed on neutral alumina and is eluted with methylenechloride-petroleum ether, affording the product in about percent yield.

EXAMPLE VI 2,7-Diacetoxyl ,3 ,6,8 ,15 ,1 6-hexamethyl-l 5 ,16-dihydropyrene l-lexamethyldihydropyrene-Z,7-quinone (500, mg) is. A

which smelled strongly of acetic acid. The residue is treated withmethanol and filtered, washed again with methanol, and dried andrecrystallized from methylene chloride/heptane, m.p. 239-240 C.

Use of other anhydrides, such as propionic anhydride, yields thecorresponding acyloxy compounds.

EXAMPLE VII The l 6-methylene-l ,3 ,6,8-tetramethyl-l 5 ,16-dihydropyrene of Preparation II is treated with acetic anhydride andcupric nitrate by the procedure of Example I;2-nitro-l5,l6-methylene-l,3,6,8-tetramethyll 5 ,l 6-dihydropyrene isobtained.

2-Nitrol 5 l 6-methylenel ,3 ,6,8-tetramethyll 5 l 6- dihydropyrene istreated with sodium acetate, acetic anhydride and zinc dust by theprocedure of Example II and 2-acetylaminol 5 ,1 -methylene- 1 ,3 ,6,8-tetramethyll 5 l 6-dihydropyrene is obtained.

2-Acetylaminol 5 l 6-methylenel 5 ,16- dihydropyrene is treated withacetic anhydride and cupric nitrate. according to the procedure ofExample II and 2-acetylamino-7-nitro-l 5, l 6-methylene-l ,3,6,8-tetramethyll 5 l -dihydropyrene is obtained.

2-Amino-7-nitro-l 5 l 6-methylenel ,3 ,6,8- tetramethyl-l5,l 6-dihydropyrene (prepared by hydrolysis of the corresponding Z-acetylaminocompound) is treated with fluoboric acid according to the procedure ofExample IV. This is then treated with sodium nitrate and 2,7-dinitrol 5l -methylenel ,3 ,6,8-tetramethyll 5 l 6-dihydropyrene is obtained.

2,7-Dinitro-l 5 I 6-methylene-l ,3 ,6,8-tetramethyll5,l6-dihydropyreneis treated with sodium acetate, acetic anhydride and zinc dust accordingto the procedure of Example V. 2,7-Diacetylamino-l5,l 6- methylene-l ,3,6,8-tetramethyll 5 I 6-dihydropyrene is obtained.

EXAMPLE VIII 2-Acetyl-l ,3 ,6,8, l 5 l 6-hexamethyll 5,1 6-dihydropyrene To a solution of 500 mg ofl,3,6,8,l5,l6-hexamethyl-l5,l6-dihydropyrene in 25 ml methylene chlorideis added dropwise over 45 minutes a solution of 0.17 ml of aceticanhydride and 0.l0 ml of stannic chloride in 25 ml of methylenechloride. After 18 hours, the reaction is poured into ice-water and thismixture is stirred until the acetic anhydride has dissolved (2 hours).The aqueous suspension is extracted with methylene chloride/ether andthese extracts are washed several times with water, dried, andconcentrated. The residue is dissolved in methylene chloride andchromatographed on silica gel. A green band elutes rapidly which isidentified as starting material. A second green band which is 2-acetyl-l,3,6,8,l5,l6-hexamethyl-l5,l 6-dihydropyrene is eluted with methylenechloride, wt. 145 mg (49 percent), m.p. 202203. Sublimation atl20-l30l0.01 mm raises the melting point to 205-206.

Use of excess acetic anhydride (e.g. 0.2 ml with 490 mg of thedihydropyrene starting material) yields 2,7-diacetyl-I,3,6,8,l5,l6-hexamethyl-l5,l6- dihydropyrene, m.p. 226-227 C.

EXAMPLE IX 2-Formyl-l ,3,6,8,l 5,1 6-hexamethyl-l 5,1 6- dihydropyrene l,3 ,6,8, l 5 l 6-I-lexamethyll 5, I 6-dihydropyrene (956 mg) isdissolved in 50 ml of dry methylene chloride and to this solution atroom temperature are added 0.5 ml of stannic chloride and 1.0 ml ofdichloromethylbutyl ether (3 mole equivalents). The

dark green solution is stirred at room temperature for 17 hours andpoured into water. The aqueous burgundy red suspension is stirred for 15minutes and extracted with methylene chloride/ether. These extracts aredried and concentrated, and the residue, in methylene chloride isapplied to a silica gel column. A dark maroon band is eluted with 3percent ethylacetate/methylene chloride. Toward the end of the elutionthe color changes from burgandy to redbrown, and a second fraction istaken. The main fraction yields 2-formyl-1,3,6,8,l5 l 6-hexamethyll 5, l6- dihydropyrene, m.p. 205-207 in about percent yield, and uponrecrystallization from methanol yields black-red needles, m.p. 206-208.

EXAMPLE X 2-Acetamido-7-formyll ,3,6,8,15,l 6-hexamethyll5 l6-dihydropyrene To a stirred solution of 400 mgof2-acetamidol,3,6,8,l5,16-hexamethyl-l5,16-dihydropyrene in 25 ml ofmethylene chloride is added 0.2 ml stannic chloride, followed by 0.4 ml.dichloromethylbutyl ether (two-fold excess). After 3.5 hours, thereaction solution is poured into water. The deep burgundy-red suspensionis stirred for 15 minutes and extracted with methylene chloride/ether.These extracts are concentrated, treated with toluene, andreconcentrated to remove traces of acetic acid. After drying in a vacuumoven at 40, the dark maroon residue is chromatographed on silica gelusing 50 percent ethyl acetate/heptane as eluting solvent to yield2-acetamido-7-formylhexamethyldihydropyrene. Recrystallization of thismaterial from methylene chloride/heptane yields the product as a darkmaroon solid, m.p. 2 l 6-2 1 8.

EXAMPLE XI 2-Benzoyl-l ,3,6,8,l5,16-hexamethyl-l 5,16- dihydropyrene Toa solution of 400 mg of l,3,6,8,l5,l6-hexamethyl-l5,16-dihydropyrene in25 ml of methylene chloride is added successively 0.16 ml of benzoylchloride and 0.20 ml of stannic chloride. The mixture is stirred for 20hours, poured into 6N hydrochloric acid and extracted with ether. Theseextracts are dried, concentrated and chromotographed on silica gel,eluting with 1:1 methylene chloride1hexane to yield, after initialelution of starting material, the desired product which isrecrystallized from methylene chloride/methanol, m.p. 22 l223 C.

EXAMPLE XIII 1 ,2,3 ,6,8 l 5 l 6-l-Ieptamethyll 5 l 6-dihydropyrene Asolution is prepared by carefully adding 6 g of lithium aluminum hydrideto a solution of 20 g of aluminum chloride in 250 ml of absolute ether,refluxing the resultant mixture for 2 hours and decanting the cooledclear supernatant. To 50 ml of this supernatant solution is added, in adropwise fashion over a 30 minute period, 400 mg ofZ-formyl-l,3,6,8,l5,l6-hexamethyl-l5,16- dihydropyrene in 20 ml oftetrahydrofuran and 50 ml of ether. The resulting slurry is heated atreflux for 1 hour, cooled and carefully treated with 30 ml of ethylacetate followed by 30 ml of water. The organic layer is separated,washed with brine, dried, and concentrated to yield the product which isfurther purified through recrystallization from methylenechloride-heptane, m.p. 2 l 42 1 5 C.

By substituting 2,7-diacetyll ,3 ,6,8,l 5, l6-hexamethyl-l5,16-dihydropyrene in the foregoing procedure, there isobtained 2,7-diethyl-l,3,6,8,l5,16- hexamethyll 5,1 -dihydropyrene.

EXAMPLE Xlll 2-Aydroxyrnethyl-l ,3,6,8,l 5,1 6-hexamethyl-l 5,16-dihydropyrene EXAMPLE XIV 2-Acetoxymethyl-l ,3,6,8, l 5, l6-hexamethyi-l 5, l 6- dihydropyrene 1 gram of 2-hydroxymethyl-l,3,6,8,l5,l6-hcxamcthyll 5,1 6-dihydropyrene, 5 ml of acetic anhydrideand 2.5 ml of pyridine is allowed to stand for hours. At the end of thistime, the mixture is poured into ice water and extracted with methylenechloride. These extracts are washed with water, dried, and evaporated toyield Z-acetoxymethyl-l,3,6,8,l5,l6-hexamethyl-15,16

-dihydropyrene, which may be further purified through recrystallizationfrom methylene chloride-heptane.

EXAMPLE XV 2-Cyano-l ,3,6,8,l 5, l 6-hexamethyl-l 5,1 6-

dhydropyrene.

To a slurry of 257 mg of2-formyl-l,3,6,8,l5,l6-hexamethyl-l5,l6-dihydropyrene in 60 ml ofethanol is added .a solution of 106 mg of hydroxylamine hydrochloride in5 ml of water which has been previously neutralized with sodiumcarbonate to pH 7-8. This mixture is heated at reflux for 15 minutes andwater is then added until crystallization begins. After cooling themixture in an ice bath, the solid is collected by filtration and driedto yield 2-formyl-l,3,6,8,l5,16- hexamethyHS,lG-dihydropyrene oxime,m.p. 206-20 8O A mixture of 244 mg of this oxime and 20 ml of aceticanhydride is heated at reflux for 15 minutes and then poured into water.This mixture is stirred until the acetic anhydride is dissolved and thenextractedvwith methylene chloride-ether. The extracts are washed withbrine, dried, and evaporated. The residue is dissolved in toluene andchromatographed on silica gel, eluting with 1:1 methylenechloride:heptane to yield the product as the initial band, mp. 21 8-2 19 C.

By employing 2-acetyl-l,3,6,8,l5,l6-hexamethyl-.

15,16dihydrcapgrene, there is similarlg obtained 2- (acetyl)- ,3,,15,l6-hexamethyl-l5,l -dihydropyreneoxime which is converted to2-cyano-l ,3,6,8,15,l6- hexamethyll 5 l -dihydropyrene.

EXAMPLE XVl The following formulation is prepared:

Gcon l03-EP polyvinyl resin 100.0 g Advaltate T 3 stabilizer 2.0 gStearic acid 0.5 g 2-Acetamido-7-nitro-l,3,6,8,l5,l6- 0.005 ghexamethyl-l 5,1 6-dihydropyrene The dihydropyrene is solvent blended(methylene chloride) with the powdered poly(-vinyl chloride) and otheradditives and the solvent is evaporated. The

batch is milled on a two-roll plastics mill for 5 minutes at 350 F. Themilled sheet is compression molded at 365 F. into four 5 5X0.045 inchsheets in a picture frame mold. (Molding cycle: 5 minutes at contactpressure; seconds at 5 tons; 45 seconds at 10 tons; 45

seconds at 15 tons; 45 seconds at 20 tons; then flash quench in coldwater.) The colored plastic films clear on exposure to light and darkenwhen left in the dark.

What is claimed is: 1. A compound which is 2-hydroxymethyll,3,6,8, l 5,16-hexamethyl-l 5, l6-dihydropyrene.

